Mechanism for stud welding guns and the like



Oct. 19, 1948. CANDY 2,451,716

MECHANISM FOR STUD WELDING GUNS AND THE LIKE Filed Sept. 28, 1946 2 Sheets'Sheet l ELECTKO Mas/v57" Odt. 19, 1948.

A. M. CANDY MECHANISM FOR STUD WELDING GUNS AND THE LIKE Filed Sept. 28, 1946 2 Sheets-Sheet 2 H/d/FK PIECE [r2 yen to)" M d} mm T.

Patented Oct. 19, 1948 MECHANISM FOR STUD WELDING GUNS AND THE LIKE Albert M. Candy, La Grange, 111., assignor, by mesne assignments, to National Cylinder Gas Company, Chicago, 111., a corporation of Delaware Application September 28, 1946, Serial No. 700,054

16 Claims.

My invention relates, generally, to driving mechanisms, and it has particular relation to such means for stud welding guns and the like.

In my copending application Serial No. 620,295, filed October 4, 1945, I have disclosed a stud welding mechanism which can be employed in the welding of studs, such as disclosed in my application Serial No. 674,994, filed June 7, 1946. By means of this stud welding gun, it is possible to weld threaded studs to a work piece at various locations over its surface. In general, the device comprises a mechanism for receiving and handling the stud so as to bring it into the desired position on the work piece. Provision is made for withdrawing the stud a short distance from the work piece, in order to strike a welding arc therebetween. It will be understood, of course, that a source of welding current is connected between the stud handling mechanism and the work piece, and that the circuit thereto is completed in the proper timed sequence so as to strike the arc and to cause current flow sufiicient to perform the necessary welding operations. After the arc is struck by withdrawing the stud from the work piece, the stud is moved to engagement with the work piece under considerable pressure, and subsequently the flow of welding current is cut off.

The present invention has particularly to do with the mechanism that is employed for withdrawing the stud from the work piece through the extent which must be controlled accurately. The present invention may be employed in conjunction with the stud welding apparatus disclosed in my copending application Serial No. 620,- 295, above referred to, and in similar welding apparatus.

The extent of movement of the stud away from the work piece to draw the arc is relatively slight. It may be of the order of its", and in general will not exceed A;". After it has been determined what is the optimum extent of movement of the stud away from the work piece to give satisfactory results, it is necessary'to maintain this extent of movement on repeated operations of the stud welding mechanism, in order to obtain uniform results. If the stud is moved too far away from the work piece, the resulting arc may be of greater extent than is necessary and too much metal may be volatilized. If the stud is not moved through a suflicient distance, the arc may not be developed to an extent sufiicient to heat the required amount of metal or to raise it to the necessary temperature to form the weld when 2 the stud is subsequently released, and moved back into engagement with the work piece.

It will be understood, of course, that the stud holding or handling mechanism should be free of the retracting mechanism prior to the initiation of the welding cycle. This facilitates the positioning of the stud in engagement with the work piece. Also, it permits the use of various engths of studs without any changes in the'stud handling apparatus that is required.

For withdrawing the stud from the work piece, a motor mechanism, such as an electromagnet, may be employed. It has been the practice to have the armature of the electromagnet move a driving rack, the teeth of which normally are out of engagement with a pinion. The pinion is arranged to operate through reduction gearing for driving a driven rack that is connected to the stud handling mechanism. Since the pinion associated with the driving rack normally is out of engagement therewith, the stud handling mechanism is free to move for properly locating the stud on the work piece. When the motor mechanism or winding of the electromagnet is energized, the driving rack is moved until the tooth thereof adjacent the pinion engages the same. Further movement of the driving rack is translated through the reduction gearing to effect the desired withdrawing movement of the stud handling mechanism.

Since the pinion normally is out of engagement with the rack, the teeth thereof bear no particular relation to the teeth of the rack that is operated by the driving motor or electromagnet. Thus, in certain positions of the pinion, the driving rack may move as much as the circular pitch width of a tooth and tooth space before d'FF ing engagement with the pinion is had. In other positions of the pinion, only a slight movement of the driving rack may be required in order to eliect the desired driving engagement.

Since the extent that the stud is withdrawn from the work piece is governed by the extent oi movement of the driving rack, it will be obvious that there may be substantial variation in the distance that the stud is withdrawn from the work piece during successive operations of the stud welding mechanism.

Accordingly, among the objects of my invention are: To place the motor mechanism or electromagnet which is energized to withdraw the stud from the work piece in a driving relation with the stud handling means with a minimum of lost motion; to permit the stud handling means to be free of engagement with the motor mech- 3 anism until the latter is energized, and then to operatively interconnect them with a minimum of movement of the motor mechanism; to interconnect the stud handling means and the motor mechanism with therack and pinion means arranged so that there is no operative relation therebetween until the latter is energized; to prevent jamming of therack and pinion teeth during the initial engagement; to relieve the pinion teeth along the top lands so as to prevent the first rack tooth from jamming against the top land of any pinion tooth and to permit engagement near the pitch circlei tq gger certain of the teeth of said rack and pinion means so that the load applied theretois' more uniformly distributed when the driving engagement takes place; to extend the tooth truie driving rack adjacent its pinion only to about beyond the pitch line so as to (still further) prevent jamming and to distribute the load; and to guide the'drivir'i'girack on itsassociated pinion so as to insure proper alignmenttherebetween. In the e of twd'staggered driving racks and pinions, it"is o'nly desirable to limit the length of the first t th f t e ad n rafiki'otner' objects ofiny invention will, in part, be obvious and in part appear hereinaiter.

My invention is disclosed and the embodiment thereof shown inQthe accompanying drawings, and itv-comprises the features of construction, combination" of elements and of parts which will be exemplified in the construction hereinafter set forthf and the scope of the, application of which will bjejirfidicated in' the appended claims.

"For a more complete understandin of the nature and scope of my invention, reference may be'hadto'the',following detailed description, taken together with the "accompanying drawings, in which: Figures 1 and 2, .talgen together with Figure 1, placed above'liig'ure'2,illustrate a stud welding gun enanis 'm which myinvention is incorgamed? I Y Figure 3 is a detail sectional view, along the line 3j 3' of"Figu1e 4, and showing the relationship betweenthe teeth of the'ipinions that are driven byithe driving racks and their .teeth', when they a are in .d'r'iving'relationj' Figure 4 is 'a view, in side elevation, of the driving racks and the associated reduction gearing,

a d showin g'the staggered relationship between theteth on'the drivingracks;

"Figurefb is a view, in front elevation, on the enlarged scale, showing a portion of the driving racks andthe teeth ins'tagg'e'red relation. thereon; ""lfri'gure fiisaview, in sideielevatiom at an enlarged scale, illustrating 'the preferred shape of the teeth of the pini'oris, and, the s hortened first tooth of. the le ading" rackla nd "Figure 7 is a view, similar to Figure 3, showing another embodiment of theinvention. Referring now particularly to Figure 2 of the drawings, it will be observed that the reference character [0 designates a work piece connected to one terminal .of a welding current source, to which the stud 'll of the kind disclosed inmy applica-v tlon Serial No. 674,99415 tobe Welded, It Will-be understood that the present invention can be emplayed with other types of stud, and that the showingof the stud l I and the reference to appli-. cation Serial No. 674,99fajre for illustrative. pup; poseslonly.

, Tnestua- IJ may-beholder frictionallygripped by, l'aws l'llof a stud niechanismf which is indicated, generally, at l3. Jaws IZ'arelo cated ar und the s a t 1.5-

at the lower end of an extension M, the upper end of which is threaded into the lower end of a shaft l5, that is mounted for sliding movement in an inner sleeve 16. The inner sleeve I6 is held in place by a nut I! that is threaded onto its upper end.

The nut l1 clamps the inner sleeve Hi to a base l8, only a portion of which is shown in Figure 2. Since the shaft l5 and inner sleeve [6 are connected to one terminal of the welding current source, it is necessary to insulate them from the base I8, and also from contact by the operator. For this purpose, there are provided an insulating washer l9 and an insulating collar 20. It will be observed that the nut 11 bears against the washer l9, which, in turn, bears against the upper surface of the base 18. Thecollar 26 extends through the base [8, and has a flange which extends along its under surface and bears against a flange 2i that may be integrally formed with inner sleeve l6 A ,mi relem,2A w s la io r un s he inn'er' sleeve [6, andextends, as shown, from the underside of thebase wand the underside of the fia ee l be ond th lowe n of he sl v It. order to bias the shaft .l5 downwardly to fs the tu int en a eme t h w r piece ID, a coil compression spring 25 is located i 'The spring reacts betweentheshoulderfi on the shaft 15 and the underside of a flange that is integrally formed withthe nut l'l. It will be understood that, when thes-tud I I is free of engagement with the work piece It, theshaft'lii will be urged by the coil compression spring 25 relative to the inner sleeve {6 outwardlyto an extent depending upon the extent that the shaft I5 is permitted to move through the nut IT as limited by suitable stops for example the lower nut 34 in Figure 1.

Surrounding the sleeve 2?. of insulation is an oute ee w Whiqh po as a b d- .iustablysecured as illustrated in my co-pending application Serial No. 520,295. The lower end of the support 3!! is flared outwardly, and comprises legs 3!, which may be secured, as by welding, to a ring 32-, the under side of which bears, as shown, against the upper surface of the work piece llli 7 Reference may now be had to Figure 1 of the drawings, where the upper extension of the shaft IBis'illuStrated; Clarnp nuts 36 may be threaded on' the shaftlf: to secure a terminal flange 35 therebetween to permit a connection to the other terminal ofthe welding source. At its upper end the shaft 15 is provided with a driven rack 35, th'e teeth of which are: indicated at 3'1. It will be understood that the driven rack 39 is connected to the shaft l5 through suitable insulating means so as to insulate the driven rack 35 andatheparts-associatedtherewith from the shaft 15; However, for illustrative purposes, and in order to disclose the, present invention more clearly, the rack 3.6 is illustratedv as being con: nectedzdirectly-tothe shaft, I5.

Theteeth 38' am i n 3 m sh w thth teeth 31 he ra k i6, a d th s en ag men no mallx-mai uained a the t eth; 3 r w y i eaeeseme twith.thee th r ni n 39 s m un ed an con-inst r ati w fe ar whe QB on a suitable shaft 4|, Fi ure 3. The gear wheel 41] haspteeth 42] which engage teeth 43 of apinio n 4.4,, which, in turn, aretari anged to eni'ieteeihq fa di et e fifi h r v ng riack l fi is mounted on a rack, carrier 4], whichha's x nsim t h itw ll. v un e s o d attached the armature of an electromagnet that is.

indicated at 49. The winding of the electromagnet 49 may be energized from a suitable source 50, which may be an alternating current source, on closure of a push button switch 5|.

The teeth 43 of the pinion 44 normally are out of engagement with the teeth 45 of the driving rack 45. Also, as will appear in more detail hereinafter, teeth 55 on a pinion 55 normally are out of engagement with teeth 51 of a driving rack 58. This permits the shaft l5 and the driven rack 38 to be moved freely so as to permit the position-- ing of the stud H in engagement with the work piece ill. This also permits various lengths of stud ii to be employed, without requiring any changes in the construction or adjustment of the stud handling mechanism 13. As the driven rack 13 is moved in positioning the stud H, corresponding movements of the pinion 39 and gear wheel 49 and pinions 44 and 55 take place.

It will be apparent that the teeth 43 of the pinion 44 are not located in any particular relation to the teeth 45 of the rack 46, so that, on operation of the electromagnet 49 the pinion 44 will be rotated to an extent which corresponds substantially to the extent which the driving rack 46 is moved. These conditions also apply to pinion 55 and leading rack 58.

Accordingly, in accordance with my invention, I have mounted the pinion 44 for rotation on a shaft 54, to which is also secured a second pinion having teeth 55 which are staggered with respect to the teeth 43 of the pinion 44, one tooth width. Thus the teeth 56 of the pinion 55 are located in register with the spaces between the teeth 43 on the pinion 44.

The teeth 56 of the pinion 55 are arranged to engage teeth 5'1 on a second driving rack 58, which teeth are in the same staggered relationship so that, as shown in Figures 4 and 5, the teeth 5'! are in register with the spaces between the teeth 45.

The pinions 44 and 55, in effect, constitute twin pinions, with their teeth in staggered relation, and they engage respectively twin racks 46 and 58, both of which are mounted on and move with rack carrier 41. Now it will be apparent that, when the electromagnet 49 is energized, and the rack carrier 41 is moved upwardly in the direction indicated by the arrow thereon, Figure 1, either the upper tooth of the set of teeth 51 will engage a tooth 55 of pinion 55 or both this engagement and the engagement of the upper tooth of the set of teeth 45 with a tooth 43 of pinion 44 will take place, depending upon the angular relation between these pinions and the racks 46 and 58.

It is desirable that the pinions 44 and 45 be accurately guided with respect to the driving racks 45 and 58. For this purpose, a washer or flange 85 may be located between the pinions 44 and 55, and it may extend into a slot 61 between the driving racks 46 and 58. The washer 60 prevents the teeth 45 and 5'! of the racks 46 and 58 from engaging too deeply the teeth 43 and 56 of the pinions 44 and 55.

In order to minimize jamming of the top tooth 52 or" the driving rack 58 with the teeth of the pinion 55, the uppermost tooth 92 of the set of teeth 5? is cut off, as indicated in Figure 4, near the pitch line, This also distributes more uniformly the load on the top two teeth of the sets of teeth 51 and the pinion teeth 43 and 56, especially when tooth 62 just misses a pinion tooth 55.

Byemploying the gear reduction which is provided by the pinion 39 and the gear wheel 49, it

is possible to use a smaller electromagnet 49 than would otherwise be the case if the pinion 44 were directly in engagement with the driven rack 39. However, it will be apparent that the reduction gearing can be dispensed with, and that the pinion 44 can be arranged to drive the driven rack 36 in lieu of the pinion 39.

As illustrated in Figure 6, the top lands 63 of the teeth 56 (likewise the corresponding top lands of teeth 43) are relieved. This eliminates the possibility of the leading edge of the first rack tooth from jamming against the top land of the next pinion tooth. This also provides that, when the first rack tooth 62 of the set of teeth 51 misses a pinion tooth, it will engage the next pinion tooth near the pinion pitch circle.

In Figure 7 of the drawings I have shown a third pinion 65 on shaft 54 which may be in driving engagement with gear wheel 49 in lieu of pinion 44. This arrangement is desirable when the teeth 43 and 56 0f the pinions 44 and 55 are relieved as described hereinbefore.

Since certain further changes can be made in the foregoing construction and different embodiments of the invention can be made without departing from the spirit and scope thereof, it is intended that all matter shown in the accompanying drawings and described hereinbefore shall be interpreted as illustrative, and not in a limiting sense.

I claim as my invention:

1. In stud welding apparatus wherein a stud to be welded to a work piece is held in a stud welding machine and is arranged to be withdrawn therefrom a short distance by longitudinal movement of a shaft in response to energization of motor means to strike a welding are between the stud and the work piece, in combination, a driven rack secured to and movable with said shaft, a driving rack arranged to be operated by said motor means, and gear means for operatively interconnecting said racks, said driving rack having a plurality of sets of teeth thereon in staggered relation and the gear means for engaging the same having a plurality of sets of teeth in the same staggered relation and being normally out of engagement therewith and arranged to engage the same on energization of said motor means whereby said engagement takes place after a minimum of movement of said driving rack.

2. The invention, as set forth in claim 1, wherein the driving rack and the gear means for engaging the same have two sets of teeth in staggered relation and the top lands of the teeth of said gear means that are engaged by the teeth of said driving rack are relieved to permit the initial engagement to take place substantially at the pitch line.

3. The invention, as set forth in claim 1, wherein the driving rack and gear means for engaging the same have two sets of teeth in staggered relation and certain of said teeth are relieved to prevent jamming of the same when the initial engagement takes place.

4. The invention, as set forth in claim 1, wherein the tooth of the driving rack adjacent the gear means extends only to near the pitch line to prevent jamming of the teeth when said driving rack is moved by the motor means and to distribute the loading of the teeth of said driving rack adjacent said gear means.

5. The invention, as set forth in claim 1, wherein guiding means operates between the driving rack and the gear means to maintain predetermined relation therebetween.

6..'Th'e invention, as set forth inclaim 1,

wherein the driving rack and' the gear means for engaging the same. have two sets of teeth. in staggeredrelation and a flange extends between said: sets; of. teeth on said gearmeans into: a slot in. said driving rack between said sets of teeth thereon.

7.. The invention, as set forth in, claim 1, wherein thegear meansincludes'a pinion incom stant engagement with the driven. rack, a gear wheel rotatable con-jointly with 'said: pinion, anda: pinion carrying two sets of teethin staggered relation. for engaging corresponding sets of teeth on the driving rack, said gear wheel being, in constant. engagement with one of said sets of teeth of the last named pinion.

8. The invention, as set forth in claim 1, wherein. the gear means: includes a pinion in constant: engagementywith the driven rack, a gear wheel rota-table con-jointly with said pinion, a pinion. carrying two sets of teeth in staggered relation for engaging corresponding sets of teeth on the driving rack, and. a pinion rotatable conjointly with the last named pinion and being. in constant engagement with said gear wheel.

9. In stud welding. apparatus wherein a studto be. welded to a work piece is. held in a stud welding machine and is arranged to be withdrawn therefrom a short distance by longitudinal movement of a shaft in response to energization of motor means to strike a welding arcbetween the stud and the'work piece, incom-bination, a driven rack secured to and movable with said shaft, 2. driving raclr arranged to be operated by said motor means, and gear means for operatively interconnectingv said racks, the teeth of the driving rack adjacent said gear means extending only to near the pitch line to prevent jamming of the teeth when said. driving rack. is moved by said motor means and to distribute the loading of the teeth of saiddrivingv rack adjacentsaidgear means- The invention, as set forth in claim. 9;. wherein the top lands of the teeth of. the gear means are relieved to permit the initial engagement by the driving rack teeth to take place substantially at the pitch line.

11. In stud welding apparatus wherein a stud to be welded to a work piece is held in a stud welding machine and isarranged-tobe-withdrawn therefrorna short distance by longitudinal movement of a shaft in response to energization' of motor means to strike. a welding are between the stud. and the work piece, in. combination, a driven rack secured to and movable with said shaft, 2.. first pinion in constant engagement with said driven rack, a gear wheel rotatable conjointly' with said pinion, a second pinion having two sets of teeth in staggered relation. of one-half tooth pitch with one set of teeth in constant driving; engagement with; said gear wheel, and a driving; rack arranged to be operated by said motor means and having two sets of teeth in the-same staggered relation as said second pinion and. normally out of engagement therewith and arranged to engagethe same onenergization of said motor means.

12. In stud welding apparatus wherein a: stud to be welded to a work piece is held in a. stud welding machine and is arranged to be with drawn therefrom a short distance by longitudinal movement of a shaft in response to energization of motor means to strike a,v welding archetween the stud; and the workpiece, in combination, a driven racksecured to and movable with saidshaft, a first pinion in constant engagement with. said driven. rack, av gear wheel. rotatable. conjointly withsaidpinion, a second pinion hav ing two sets of teeth in staggeered relation, of. one-half tooth pitch with one set of teeth-in constant, driving engagement with said gear wheel, and a driving rack arranged to be operated by said mOtOt means and having two sets of teeth in. the. same staggered relation as said. second pinion and normally out of engagement. there-.- with and. arrangedtoengage the same on energization of said motor means, the top lands of the teeth of said pinion. that are engaged by the corresponding teeth ofsaid driving, rack being, relieved. to permit. the initial engagement to take. place substantially at the pitch line.

13. In stud welding apparatus wherein a stud tobe welded to a work piece is held in a. stud welding machine and is arranged to be with.- drawn therefrom a short distance by longitudinal movement of a shaft in response to energizationof motor means to strike a welding are between the stud and the workpiece, in combination, a driven rack secured to and movable with saidshaft, a first pinion in constant engagement with said driven rack, a gear wheel rotatable conjointly with said pinion, asecondpinion having. two sets of teeth inv staggered relation of one-half tooth pitch with one-set of teeth in constant driving engagement with said gear wheel, and a driving rack arranged to be operated by said motor means and having two sets of teeth in the same staggered relation as said second pinion and normally out of engagement there r with and arranged to engage the same on energization of said motor means, the teeth of said second pinion being relieved in such manner as to prevent jamming with the teeth-of said driving rack when the initial engagement thereof takes place.

14. In stud welding apparatus wherein a stud to-be welded toa work piece is held ina stud-welding machine and is arranged to be withdrawn therefrom a short distance by longitudinal movement of a shaft in response to energization of motor means. to strike-a welding are between the stud and the work piece, in combination, a driven rack secured to and movable. with said shaft, a first pinion in constant engagement with said drivenrack, a gear wheel rotatable conjointly with said pinion, a secondpinion having two sets of teethinstaggered relation of one-half tooth pitch with one set of teeth in constant driving engage ment with said-gear wheel, a driving rack arranged to be operated by said motor means and having two sets of teeth in the same staggered relation as said second pinion and normally out of.engagement-therewith and arranged to engage the same on energization of said motor means, and a flangeextending radially from said second pinion intoa slot in said driving rack forguiding the same in their relative movement.

1511p stud welding apparatus whereina stud to be welded to a Work piece is held inastudwelding machine and is arranged to be withdrawn therefrom ashort distance by longitudinal movement of. a shaft in response to energization of motor means to strike awelding arcbetween the stud and. thework piece, in combination, a driven rack secured to and movable with said shaft, a first. pinion in constant engagement with said drivenrack, a gear wheel rotatable conj ointly with said pinion, a second pinion having two setsv of teeth.instaggered'relation ofone-half tooth pitch with one. set ofv teeth-in constant driving. engagement with said gear wheel, a driving rack arranged to be operated by said motor means and having two sets of teeth in the same staggered relation as said second pinion and normally out of engagement therewith and arranged to engage the same on energization of said motor means, and a flange extending radially between said two sets of teeth on said second pinion into a slot between said two sets of teeth on said driving rack.

16. In stud welding apparatus wherein a stud to be welded to a work piece is held in a stud welding machine and is arranged to be withdrawn therefrom a short distance by longitudinal movement of a shaft in response to energization of motor means to strike a welding are between the stud and the work piece, in combination, a driven rack secured to and movable with said shaft, a first pinion in constant engagement with said driven rack, a gear wheel rotatable conjointly with 0 said pinion, a second pinion having two sets of teeth in staggered relation of one-half tooth pitch with one set of teeth in constant driving engagement with said gear wheel, and a driving rack arranged to be operated by said motor means and having two sets of teeth in the same staggered relations as said second pinion and normally out of engagement therewith and arranged to engage the same on energization of said motor means, the tooth of said sets of teeth on said driving rack nearer to said second pinion extending only to near the pitch line to prevent jamming of the teeth when said driving rack is moved by said motor means and to distribute the loading between the first teeth of said sets of teeth on said driving rack.

ALBERT M. CANDY.

REFERENCES CITED UNITED STATES PATENTS Number Name Date Hughes et al. Dec. 9, 1941 

